CN110735724A

CN110735724A - Method and system for braking compound engine

Info

Publication number: CN110735724A
Application number: CN201810791269.4A
Authority: CN
Inventors: 杨洲; 奚勇
Original assignee: Shanghai Youshun Automobile Parts Co Ltd
Current assignee: Shanghai Youshun Automobile Technology Co.,Ltd.
Priority date: 2018-07-18
Filing date: 2018-07-18
Publication date: 2020-01-31
Anticipated expiration: 2038-07-18
Also published as: CN110735724B

Abstract

The invention provides composite engine braking method and system, which is used for an engine with a turbocharger, the engine is provided with an engine brake, the engine brake is used for opening exhaust above a cylinder in the engine to release gas compressed in the cylinder of the engine during the compression stroke of the engine into an exhaust manifold, an air supercharging mechanism is additionally arranged and used for controlling the running speed of the turbocharger to adjust the air inlet pressure and the exhaust pressure of the engine, the air supercharging mechanism needs to be started when the engine is braked to judge whether compressed air is available, and the composite engine brake is executed if the compressed air is available, so that the engine brake and the air supercharging mechanism are started.

Description

Method and system for braking compound engine

Technical Field

The invention relates to the field of engines, in particular to a braking method and a braking system for composite engines.

Background

The main difference between engine braking and ignition operation is that the engine, which produces power, is temporarily converted to an energy absorbing air compressor without fuel injection and combustion during braking, except for the conventional intake and exhaust opening during the intake and exhaust strokes, the exhaust opens again near the top compression dead center of the engine piston, allowing the compressed gas (air during braking) to be released, the energy absorbed by the compressed gas during the compression stroke of the engine, not returning to the piston of the engine on the subsequent expansion (power) stroke, but being released through the exhaust and heat removal system of the engine.

The power and load of engine braking are increased along with the increase of the rotating speed, the engine mostly runs at the middle and low rotating speeds in practical use, and how to improve the engine braking power at the middle and low rotating speeds is urgent under the premise of not increasing the braking load (without overload). It is conventional practice to combine braking, adding exhaust back pressure braking (out-of-cylinder braking) on the basis of compression release, such as adding an exhaust butterfly valve. The combined brake can improve the brake power of medium and low rotating speeds, reduce brake load and eliminate brake noise, but the back pressure control device greatly reduces or even eliminates exhaust gas flow, so that the turbocharger does not work, reduces or even eliminates intake pressure and gas flow and has corresponding cooling effect, so that the exhaust temperature is increased, and certain parts of the engine, such as an oil nozzle, are overheated. An effective method for solving the above problems is to use a variable exhaust back pressure control device, but the additional problems caused thereby are cost increase, space increase, and complicated control.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention provides braking methods and braking systems for hybrid engines, which are used to solve the problems of complicated mechanism, high cost, large volume, difficult control of the back pressure control device of the engine, the turbocharger not operating caused by the back pressure control device, too high exhaust temperature of the engine at high rotation speed, and overheating of the nozzle tip of the fuel nozzle in the prior art.

To achieve the above and other related objects, the present invention provides methods of compound engine braking for an engine with a turbocharger, the engine having an engine brake for opening exhaust of a cylinder in the engine to release gas compressed in the engine cylinder during a compression stroke of the engine into an exhaust manifold, air pressurization mechanisms being added for varying an operating speed of the turbocharger to adjust an intake pressure and an exhaust pressure of the engine, the method comprising the steps of:

a) judging whether the engine needs to be braked when the engine runs at a certain rotating speed;

b) if the engine braking is needed, judging whether the conditions required by the engine braking are met;

c) if the conditions required by engine braking are met, judging whether the air supercharging mechanism needs to be started or not;

d) if the air supercharging mechanism does not need to be started, directly starting an engine brake for braking;

e) if the air pressurization mechanism needs to be started, judging whether compressed air is available; if compressed air is available, compound engine braking is performed, and the engine brake and the air pressurization mechanism are activated.

Preferably, an exhaust gas flow passage is provided between an exhaust manifold of the engine and a turbine blade of a turbine of a turbocharger, and the air supercharging mechanism is activated in the step e) and injects air into the exhaust gas flow passage.

Preferably, the direction in which the air pressurizing mechanism injects air into the exhaust passage includes three options:

A) an acute angle is formed with the direction of the exhaust airflow in the exhaust flow passage;

B) at right angles to the direction of the exhaust gas flow in the exhaust gas flow passage;

C) at an obtuse angle to the direction of the exhaust gas flow in the exhaust gas flow passage.

Preferably, an air inlet is arranged on a turbine housing of the turbocharger, the air pressurization mechanism is started in the step e), and the air pressurization mechanism sprays air onto turbine blades in the turbine through the air inlet.

Preferably, a gas injection hole is formed in a compressor housing of the turbocharger, the air pressurization mechanism is started in the step e), and the air pressurization mechanism injects air to a compression impeller in the compressor through the gas injection hole.

Preferably, the engine brake is a compression release type engine brake, or a bleeder type engine brake.

The invention also provides an composite engine braking system, which is used for an engine with a turbocharger, wherein an exhaust connected with an exhaust manifold is arranged on a cylinder of the engine, an exhaust flow passage is arranged between the exhaust manifold and a turbine blade of a turbine of the turbocharger, the engine also comprises an engine brake, the engine brake opens the exhaust of the engine near the compression top dead center of the engine, so that gas compressed in the cylinder during the compression stroke of the engine is released into the exhaust manifold, the composite engine braking system comprises an air supercharging mechanism, the air supercharging mechanism comprises an air compressor or an air storage tank, a control valve and an air outlet pipe, and the air outlet pipe injects air to the turbocharger to control the running speed of the turbocharger.

Preferably, the end of the outlet pipe comprises a fitting or a nozzle.

Preferably, the outlet pipe injects air to the turbocharger through an exhaust runner between the exhaust manifold and the turbocharger.

Preferably, the inlet of the turbine of the turbocharger is connected with the outlet of the exhaust manifold, and the end of the outlet pipe is arranged at the connection position.

Preferably, an air inlet hole is formed in a turbine shell of the turbocharger, and the end of the air outlet pipe is communicated with the air inlet hole.

Preferably, a compressor housing of the turbocharger is provided with a gas injection hole, and the end of the gas outlet pipe is communicated with the gas injection hole.

Preferably, the air pressurizing mechanism further comprises a check valve.

As mentioned above, the method and the system for braking the compound engine have the following beneficial effects: the air booster mechanism is used for controlling the running speed of the turbocharger, adjusting the air inlet pressure and the exhaust pressure of the engine and improving the braking performance of the engine without arranging any metal valve body or physical obstacle in a flow passage of the engine or the turbocharger.

Drawings

FIG. 1 is a schematic representation of general structures of the compound engine braking system of the present invention.

FIG. 2 is a schematic diagram of the control flows of the compound engine braking method of the present invention.

FIG. 3 is a schematic representation of an embodiment of the engine in the compound engine braking system of the present invention.

FIG. 4 is a schematic representation of another embodiment of the engine in the compound engine braking system of the present invention.

Description of the element reference numerals

12 air intake manifold

13 air inlet shunting node

14 total intake pipe

20 turbo charger

222 axle

228 turbine

218 compressor

22 exhaust manifold

23 exhaust manifold junction

24 exhaust channel

25 joint

30 engines

33 piston

35 air cylinder

40 air supercharging mechanism

41 air compressor

45 control valve

43 airway tube

47 air outlet pipe

48 nozzle

100 engine brake

120 intercooler

140. 400 air

200 inlet air

300 exhaust

211. 212 entry of turbine

240 tail pipe

500 oil nozzle

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be noted that, referring to fig. 1-4, the drawings provided in this embodiment are only schematic and illustrate the basic concept of the present invention, and only the components related to the present invention are shown in the drawings rather than being drawn according to the number, shape and size of the components in actual implementation, the type, number and ratio of the components in actual implementation can be random changes, and the layout of the components may be more complicated.

Fig. 1 is a schematic diagram of a general arrangement of cylinders of a hybrid engine braking system of the present invention, engine having a plurality of cylinders, such as a diesel engine on a commercial vehicle, in-line with six cylinders, but for simplicity fig. 1 shows only cylinders 35 of engine 30, piston 33 reciprocating in cylinder 35, four-stroke engine 30 comprising an intake stroke, a compression stroke, an expansion (or power) stroke, and an exhaust stroke every cycles of motion, piston 33 moving from top-dead-center to bottom-dead-center (i.e., piston 33 moving downward in fig. 1) in the intake stroke, intake of the engine opening to introduce air into engine cylinder 35, followed by the compression stroke, piston 33 moving from bottom-dead-center to top-dead-center (i.e., piston 33 moving upward in fig. 1, i.e., in the direction of the arrow), intake and exhaust of the engine being closed, air in cylinder 35 being compressed, air reaching the top-dead-center in the vicinity of piston 33, and after the piston 33 has reached the top-dead-center, piston 33 moving back to top-dead-center (i.e., piston 33 moving upward in the direction of the piston 33, after the compression stroke, compressing the piston 33, compressing the exhaust stroke, and injecting the exhaust stroke, as a new cycle, injecting fuel injection stroke, and injecting the exhaust stroke, the exhaust stroke after the.

The present embodiment provides hybrid engine braking systems, as shown in fig. 1, for an engine 30 with a turbocharger 20, in which the intake 200 of a cylinder 35 is connected to the outlet of the compressor 218 of the turbocharger 20 through a manifold 14, the cylinder 35 is also provided with an exhaust 300 connected to the exhaust manifold 22, the engine is provided with an engine brake 100 for opening the exhaust of the engine near top dead center of compression of the engine to release the gas compressed in the cylinder 35 during the compression stroke of the engine into the exhaust manifold 22, the hybrid engine braking system includes an air booster mechanism 40, the air booster mechanism 40 includes an air compressor 41 or air reservoir, a control valve 45, and an outlet pipe 47, the end face of the outlet pipe 47 may be provided with a nozzle 48 (or joint) for injecting gas into the turbocharger 20 to control the operating speed of the turbocharger, the present embodiment does not require any metal valve or solid block in the exhaust 240 of the engine or the turbocharger 20, but rather the operating speed of the turbocharger 20 is controlled by the air booster mechanism 40 to adjust the intake pressure and exhaust pressure of the engine, the present invention may not only improve the cooling of the turbocharger 20, but also may not affect the operation of the turbocharger 20 and the operation of the turbocharger.

The turbocharger 20 of the prior art is generally provided with the turbocharger 20 shown in fig. 1 to improve the power and efficiency of the engine, the turbocharger 20 of the present embodiment includes the turbine 228 and the compressor 218 connected by the shaft 222, the exhaust manifold 22 connected to each cylinder 35 is connected to the exhaust runner (exhaust pipe) 24, the exhaust runner 24 leads to turbine blades in the turbine 228, the exhaust gas (air during braking) from the cylinder 35 is collected from the exhaust manifold 22 into the exhaust runner 24, the turbine 228 is driven to rotate the compressor 218 coaxial with the cylinder 222, the air 140 entering from the engine intake inlet is compressed to increase the intake pressure in the total intake pipe 14, the total intake pipe 14 is divided into a plurality of intake manifolds 12 through an intake dividing node 13 as required, each intake manifold 12 is connected to the intake 0200 of the cylinder 35, the efficiency of the engine is reduced due to the increased temperature of the compressed air, the compressed air is cooled by the intercooler 120 before entering the cylinder 35 of the engine, then divided by the intake dividing node 13, the intake manifold 12 and the intake manifold 35, the intake manifold 1200 and the intake manifold 35, the exhaust pressure of the turbocharger 35, the turbocharger 20, the turbocharger 12, the turbocharger 35, the turbocharger 12, the turbocharger 300, the turbocharger 12, the turbocharger 300, the turbocharger 12.

In FIG. 1, an engine brake 100 is symbolically disposed above the exhaust 300 for opening the engine exhaust 300 near the top dead center of compression of the engine 30, releasing the gases compressed in the cylinder 35 during the engine compression stroke into the exhaust manifold 22, creating an exhaust flow at the junction 23 of the exhaust manifolds into the exhaust runner 24. in this embodiment, the engine brake 100 may be a compression release, bleeder, or other type of engine brake.A flow path 24 leads to the turbine blades through a joint 25 (the joint 25 may also be the inlet 211 of the turbine 228, see FIGS. 3 and 4 below). The exhaust flow exits from the exhaust tailpipe 240 after driving the turbine blades.A turbine blade of the turbine 228 in this embodiment has an outside diameter that is not the same in the axial direction.

In the embodiment of FIG. 1 having air booster mechanisms 40, air booster mechanisms 40 are used to inject air into the exhaust runner 24 downstream of the exhaust manifold 22 (in this embodiment, the exhaust runner 24 extends between the turbine blades inside the turbine 228), and the injected air is used to control the exhaust flow entering the turbine 228 and the operating speed of the turbocharger 200, thereby adjusting the exhaust pressure, intake pressure and intake flow of the engine, optimizing the performance of engine braking.

Since the vehicle-mounted compressed air is mainly used for controlling or operating the brake, whether the vehicle-mounted compressed air can be used for air pressurization braking for engine braking or not is determined according to the running condition of the vehicle, however, the vehicle-mounted compressed air can be effectively utilized by designing control programs.

FIG. 2 is a schematic control flow diagram of control processes of the compound engine braking method of the present invention, which can be implemented by the compound engine braking system, and includes the following steps:

In the process of engine braking, the invention judges whether the air supercharging mechanism needs to be started or not to execute compound engine braking, starts the engine brake and the air supercharging mechanism, controls the running speed of the turbocharger by using the air supercharging mechanism, adjusts the air inlet pressure and the exhaust pressure of the engine and improves the braking performance of the engine.

Specifically, as shown in fig. 2, initially assuming that the engine is operated at rpm, if the engine brake is not required or the engine brake condition is not satisfied (e.g., the engine rpm is not high enough, the clutch is not engaged, etc.), the control unit (ECU) of the engine performs a non-braking (e.g., ignition) operation control, i.e., the above steps a) -b), conversely, if the engine brake is required and the engine brake condition is satisfied, it is necessary to determine whether air boost is required, i.e., the above step c), if air boost is not required (e.g., the brake rpm is too high, the brake load is too large, etc.), the engine brake is turned on, i.e., the above step d), but if air boost is required (e.g., middle or low rpm braking), the compound engine brake is performed, i.e., the engine brake and the air boost mechanism are turned on, the exhaust gas is turned on by the engine brake , the operating speed of the turbocharger is improved by the air boost mechanism, i.e., the above step e., the above step e), it is determined whether to continue braking during braking, if the braking is continued, the.

Example 1:

embodiments of the above described compound engine braking system are illustrated by step in FIG. 3. the engine 30 illustrated in FIG. 3 is an in-line four cylinder engine, the four cylinders 35 being identified as C1, C2, C3 and C4, respectively, each cylinder releasing gas from the cylinders 35 to the exhaust manifold 22 during engine braking forms an exhaust gas flow into the exhaust runner 24 at the junction 23 and into the inlet 211 of the turbine at the junction 25 where the exhaust runner 24 joins the turbine 228. accordingly, there are only exhaust runners 24 and the inlets 211 of turbines in this embodiment, the air booster mechanism nozzle 48 is positioned at the junction 25 of the exhaust runner 24 and the inlet of the turbine, and compressed air is injected into the exhaust runner 24 near the inlet 211 of the turbine.

In the present embodiment, the air supercharging mechanism is activated to inject air into the exhaust passage, thereby changing the flow of air between the turbine blades of the turbine in the turbocharger and changing the rotational speed of the turbine blades. The direction of the compressed air injected into the exhaust passage by the air pressurizing mechanism in this embodiment may be: perpendicular to the exhaust gas flow direction in the exhaust gas flow passage 24; or at an acute angle to the direction of exhaust gas flow in the exhaust gas flow path 24 (i.e., downward into the turbine 228 in fig. 3), which may be more advantageous to increase the flow between the turbine blades of the turbine in the turbocharger, increasing the rotational speed of the turbine blades; or at an obtuse angle to the direction of exhaust gas flow within the exhaust gas flow passage 24 (i.e., upward into the exhaust gas flow passage 24 in figure 3).

Example 2:

a second embodiment of the above described compound engine braking system is illustrated in FIG. 4 by . the engine 30 illustrated in FIG. 4 is an in-line six cylinder engine, the six cylinders 35 being identified individually as groups of C1, C2, C3, C4, C5 and C6. cylinders (e.g., the first three cylinders C1, C2 and C3 or the last three cylinders C4, C5 and C6) . the group of cylinders share of the above described exhaust runner 24. during engine braking, the gas released from the cylinders 35 into the exhaust manifold 22 forms an exhaust gas flow at the junction 23 into the exhaust runner 24 and into the

turbine inlet

211 or 212 at the junction 25 where the exhaust runner 24 connects to the turbine 228. accordingly, both exhaust runners 24 and the two

turbine inlets

211, 212 of the present embodiment are provided with nozzles of an air booster mechanism positioned at the junction 25 of the outlet of the exhaust runner 24 to the turbine inlet, selectively injecting compressed air into the two turbine inlets 211, but also two exhaust runners 24, alternatively two exhaust runners , in the present embodiment.

In the present embodiment, the air supercharging mechanism is activated to inject air into the exhaust passage, thereby changing the flow of air between the turbine blades of the turbine in the turbocharger and changing the rotational speed of the turbine blades. The direction of the compressed air injected into the exhaust passage by the air pressurizing mechanism in this embodiment may be: perpendicular to the direction of exhaust gas flow within the exhaust gas flow passage 24, or at an acute angle to the direction of exhaust gas flow within the exhaust gas flow passage 24 (i.e., downward into the turbine 228 in fig. 4), or at an obtuse angle to the direction of exhaust gas flow within the exhaust gas flow passage 24 (i.e., upward into the exhaust gas flow passage 24 in fig. 4).

Example 3:

the third embodiment of the compound engine braking system is not shown in the drawing, wherein air inlet holes are arranged on the turbine shell of the turbocharger 20, and the end part of the air outlet pipe is communicated with the air inlet holes.

Example 4:

according to the braking requirement of the engine, when the air supercharging mechanism is started, a vehicle-mounted air compressor or an air storage tank is utilized to directly inject compressed air onto the compression impeller from the air injection hole on the compressor shell through the control valve and the air outlet pipe, so that the rotating speed of the compression impeller is increased, the air inlet quantity and the air inlet pressure are improved, and the braking power generated by the engine brake is increased.

The above description contains many specific embodiments which should not be construed as limiting the scope of the invention but rather as representative of specific examples of the invention from which many other variations are possible, for example, the hybrid engine braking approach herein may be used with various engines including overhead cam and pushrod engines, single-cylinder engines, and multi-cylinder engines having more than two cylinders .

Also, the air pressurization mechanism herein may vary in composition, shape, installation, regulation, etc. For example, the nozzle at the end of the outlet pipe may be flat, circular truncated cone, circular hole, ring, or the like.

Furthermore, the nozzle or fitting at the end of the outlet tube can be placed in different ways at different locations.

The timing, flow rate, and direction of the compressed air injected by the air charging mechanism may be adjusted according to the demand for braking power, the limitation of the braking load, the source of the compressed air, and the like.

Further, the air boost mechanism may inject air at or more locations.

Also, the cross section of the exhaust flow path may be other than square or circular.

In summary, the method and the system for braking a hybrid engine according to the present invention do not require any metal valve or physical obstacle in the intake air flow passage of the engine, but control the operation speed of the turbocharger through the air pressurization mechanism, adjust the intake pressure and the exhaust pressure of the engine, and improve the braking performance of the engine. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

It will be appreciated by those skilled in the art that modifications and variations can be made to the disclosed embodiments without departing from the spirit and scope of the invention, and therefore, is equivalent to modifications and variations that would be apparent to those skilled in the art without departing from the spirit and scope of the invention as disclosed in the appended claims.

Claims

A method of braking compound engine for an engine with a turbocharger, wherein the engine is provided with an engine brake for opening exhaust of a cylinder in the engine to release gas compressed in the engine cylinder during a compression stroke of the engine into an exhaust manifold, an air boost mechanism is added for changing an operating speed of the turbocharger to adjust an intake pressure and an exhaust pressure of the engine, the method of braking the compound engine comprising the steps of:

a) judging whether the engine needs to be braked when the engine runs at a certain rotating speed;

b) if the engine braking is needed, judging whether the conditions required by the engine braking are met;

c) if the conditions required by engine braking are met, judging whether the air supercharging mechanism needs to be started or not;

d) if the air supercharging mechanism does not need to be started, directly starting an engine brake for braking;

e) if the air pressurization mechanism needs to be started, judging whether compressed air is available; if compressed air is available, compound engine braking is performed, and the engine brake and the air pressurization mechanism are activated.
2. The method of compound engine braking as defined in claim 1, wherein: an exhaust gas flow passage is provided between an exhaust manifold of the engine and a turbine blade of a turbine of a turbocharger, and the air supercharging mechanism is activated in step e) and injects air into the exhaust gas flow passage.
3. The method of compound engine braking as defined in claim 2, wherein: the direction of the air injection mechanism to inject air into the exhaust channel comprises the following three options:

A) an acute angle is formed with the direction of the exhaust airflow in the exhaust flow passage;

B) at right angles to the direction of the exhaust gas flow in the exhaust gas flow passage;

C) at an obtuse angle to the direction of the exhaust gas flow in the exhaust gas flow passage.
4. The method of compound engine braking as defined in claim 1, wherein: an air inlet is formed in a turbine shell of the turbocharger, the air pressurization mechanism is started in the step e), and the air pressurization mechanism sprays air onto turbine blades in the turbine through the air inlet.
5. The method of compound engine braking as defined in claim 1, wherein: and e) a gas injection hole is formed in a compressor shell of the turbocharger, the air pressurization mechanism is started in the step e), and the air pressurization mechanism injects air onto a compression impeller in the compressor through the gas injection hole.
6. The method of compound engine braking as defined in claim 1, wherein: the engine brake is a compression release type engine brake or a bleeder type engine brake.
The combined type engine braking system is used for an engine with a turbocharger, exhaust connected with an exhaust manifold is arranged on a cylinder of the engine, an exhaust flow passage is arranged between the exhaust manifold and a turbine blade of a turbine of the turbocharger, and the combined type engine braking system is characterized by further comprising an engine brake, the engine brake opens exhaust of the engine near a compression top dead center of the engine to release gas compressed in the cylinder during a compression stroke of the engine into the exhaust manifold, the combined type engine braking system comprises an air pressurization mechanism, the air pressurization mechanism comprises an air compressor or an air storage tank, a control valve and an air outlet pipe, and the air outlet pipe injects air to the turbocharger to control the running speed of the turbocharger.
8. The system of claim 7, wherein: the end of the outlet pipe comprises a fitting or a nozzle.
9. The system of claim 7, wherein: and the air outlet pipe injects air to the turbocharger through an exhaust runner between the exhaust manifold and the turbocharger.
10. The system of claim 7, wherein: the inlet of the turbine of the turbocharger is connected with the outlet of the exhaust manifold, and the end part of the air outlet pipe is arranged at the connecting part.
11. The system of claim 7, wherein: an air inlet hole is formed in a turbine shell of the turbocharger, and the end of the air outlet pipe is communicated with the air inlet hole.
12. The system of claim 7, wherein: and a gas injection hole is formed in a compressor shell of the turbocharger, and the end part of the gas outlet pipe is communicated with the gas injection hole.
13. The system of claim 7, wherein: the air pressurization mechanism further comprises a one-way valve.
14. The system of claim 7, wherein: the engine brake is a compression release type engine brake or a bleeder type engine brake.